It is necessary for a nonvolatile semiconductor memory device to reduce the power consumption, microfabricate the elements, reduce the cost, increase the recording density and the ON/OFF ratio, and improve the rewrite durability and the data retention characteristic as the capacity of the nonvolatile memory increases.
In particular, a phase change memory (PC-RAM: Phase Change Random Access Memory) is a nonvolatile semiconductor memory device that writes/erases/reads information using the fact that the electrical resistance of a phase change film changes between a crystalline state and an amorphous state.
To obtain a desired electrical resistance change in this phase change memory, the phase change film needs to be heated almost to the melting point or to the crystallization temperature or more. In addition, a relatively large volume and power are required. For these reasons, it is difficult to solve the above-described problems including the microfabrication and the reduction of power consumption. Hence, a technique of solving these problems is demanded.